Jinping Xiong

The effects of some anions on metastable pitting of 316L stainless steel

Abstract The effects of PO 4 3− , CrO 4 2− , SO 4 2− and NO 3 − anions on metastable pitting of 316L stainless steel in NaCl solutions were investigated using potentiostatic and potentiodynamic polarization tests. The four anions all retard nucleation of metastable pitting. The inhibition effect decreases in the order: PO 4 3− >CrO 4 2− >SO 4 2− >NO 3 − . The propagation rates of metastable pits are also decreased by the anions tested. Both metastable pitting potential E m and stable pitting potential E p increase almost linearly with the increase of each anion concentration, and have very close increasing slopes.

The aspect ratio of surface grooves and metastable pitting of stainless steel

Abstract The metastable pitting behavior of 316L stainless steel with different surface roughness in 0.01 M NaCl solution was studied using potentiostatic and potentiodynamic polarization methods and statistical treatments. As surface roughness decreased, the nucleation rate of metastable pits decreased. The peak current of metastable pits also decreased, but the average growth rate of metastable pits showed a slight increase. The aspect ratio of surface groove, w / d , was suggested to characterize the openness of surface grooves, in which w is the width of the groove at the opening and d the depth of the groove. Bigger w / d value indicates more smooth surface, and it is more difficult for micro-pit to nucleate. Under certain conditions of solution and potential, there is a critical w / d value. Metastable pits may nucleate only on those surfaces whose w / d values are less than the critical value. As the aspect ratio w / d increases, the nucleation rate of metastable pits decreases linearly, and both metastable pitting potential E m and pitting potential E p move in the positive direction.

Hydroxyapatite Coatings on Titanium Prepared by Electrodeposition in a Modified Simulated Body Fluid

Abstract Hydroxyapatite coatings were directly prepared on anodized titanium by electro-deposition method in a modified simulated body fluid. The configuration, structure and bioactivity of the coating were investigated with scanning electron microscopy (SEM), X-ray diffraction analyzer (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. The results demonstrated that pure and homogeneous hydroxyapatite coating can be obtained without any post-treatment. The prepared coating showed good bioactivity in simulated body fluid (SBF). The time required for a fully covered dense hydroxyapatite coatings was 4 days immersion in SBF.

Composition and corrosion resistance of palladium film on 316L stainless steel by brush plating

Abstract Palladium films with good adhesive strength were deposited on 316L stainless steel by brush plating. Scanning electronic microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy (XPS), mass loss tests and electrochemical methods were used to study the properties of the films. The brush plated palladium film mainly consisted of palladium. XPS analysis indicated that palladium was present in the films as metal state. The palladium plated stainless steel samples showed excellent corrosion resistance in boiling 20% H 2 SO 4 solution and boiling acetic/formic acids with 0.005 mol/L Br − ions added. The corrosion rates of the palladium plated 316L stainless steel samples were about two orders of magnitude lower than those of the original 316L stainless steel samples. This method provides a possibility to prepare protective palladium films on stainless steel facilities with large areas in industrial sites.